A program was established in 1984 to study how cells regulate motility during development. The Program now includes four projects: 1) the regulation of basic cell motility and chemotaxis, and the elucidation of underlying regulatory pathways by mutant analysis in Dictyostelium; 2) the role of tropomyosin, tropomyosin-interacting proteins and myosin Va in motility and cytokinesis; 3) the role of Ca, second messengers, vesicle trafficking, and myosin Va in the development and motility of cultured Drosophila giant neurons; and 4) the development of computer-assisted 2D and 3D Dynamic Image Analysis Systems (DIAS) for the reconstruction and motion analysis of subcellular components, cells, organs and embryos. The Program core facility supports all motion analysis experiments performed by projects I through III, and collaborative studies by non-program scientists, when possible. This includes rigorous training regimes and continued supervision. The program supports the biannual Junior Motility Symposium, annual Motility Symposium, seminars by outside speakers, the annual lecture course Topics in Cell Motility and the laboratory course Biological Imaging and Microscopy. In the next Program period, the Program will continue to support the three basic research projects, the development of the next generation DIAS 4.0, symposia, seminars and courses, and the core facility. The Program, due to the development of the unique 2D and 3D computer-assisted dynamic reconstruction and motion analysis systems, has impacted not only the scientists in the Program and within the University, but also scientists world wide who either have acquired Facility-developed technologies, or who have accessed these technologies through visits and collaborations. The Program will continue to maintain its vitality, identity and integration by focusing on the fundamental question of how cells move during development, and on pioneering technologies that measure cell motility.